1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/bitops.h> 3 #include <linux/fault-inject-usercopy.h> 4 #include <linux/instrumented.h> 5 #include <linux/uaccess.h> 6 #include <linux/nospec.h> 7 8 /* out-of-line parts */ 9 10 #ifndef INLINE_COPY_FROM_USER 11 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) 12 { 13 unsigned long res = n; 14 might_fault(); 15 if (!should_fail_usercopy() && likely(access_ok(from, n))) { 16 /* 17 * Ensure that bad access_ok() speculation will not 18 * lead to nasty side effects *after* the copy is 19 * finished: 20 */ 21 barrier_nospec(); 22 instrument_copy_from_user_before(to, from, n); 23 res = raw_copy_from_user(to, from, n); 24 instrument_copy_from_user_after(to, from, n, res); 25 } 26 if (unlikely(res)) 27 memset(to + (n - res), 0, res); 28 return res; 29 } 30 EXPORT_SYMBOL(_copy_from_user); 31 #endif 32 33 #ifndef INLINE_COPY_TO_USER 34 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) 35 { 36 might_fault(); 37 if (should_fail_usercopy()) 38 return n; 39 if (likely(access_ok(to, n))) { 40 instrument_copy_to_user(to, from, n); 41 n = raw_copy_to_user(to, from, n); 42 } 43 return n; 44 } 45 EXPORT_SYMBOL(_copy_to_user); 46 #endif 47 48 /** 49 * check_zeroed_user: check if a userspace buffer only contains zero bytes 50 * @from: Source address, in userspace. 51 * @size: Size of buffer. 52 * 53 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for 54 * userspace addresses (and is more efficient because we don't care where the 55 * first non-zero byte is). 56 * 57 * Returns: 58 * * 0: There were non-zero bytes present in the buffer. 59 * * 1: The buffer was full of zero bytes. 60 * * -EFAULT: access to userspace failed. 61 */ 62 int check_zeroed_user(const void __user *from, size_t size) 63 { 64 unsigned long val; 65 uintptr_t align = (uintptr_t) from % sizeof(unsigned long); 66 67 if (unlikely(size == 0)) 68 return 1; 69 70 from -= align; 71 size += align; 72 73 if (!user_read_access_begin(from, size)) 74 return -EFAULT; 75 76 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 77 if (align) 78 val &= ~aligned_byte_mask(align); 79 80 while (size > sizeof(unsigned long)) { 81 if (unlikely(val)) 82 goto done; 83 84 from += sizeof(unsigned long); 85 size -= sizeof(unsigned long); 86 87 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 88 } 89 90 if (size < sizeof(unsigned long)) 91 val &= aligned_byte_mask(size); 92 93 done: 94 user_read_access_end(); 95 return (val == 0); 96 err_fault: 97 user_read_access_end(); 98 return -EFAULT; 99 } 100 EXPORT_SYMBOL(check_zeroed_user); 101